And so here is the Nokia Lumia 900, the top-of-the-line Windows Phone from Nokia that arrives almost a year after Microsoft and Nokia first teamed up. The Lumia 900 will go on sale "in the coming months," according to a press release, and will be available exclusively on AT&T to begin. Elop emphasized the Lumia 900's 4.3-inch AMOLED display screen, an 8 megapixel rear-facing camera with Carl Zeiss optics and a front-facing 1MP camera with built-in video calling capability. The Lumia 900 will ship with ESPN, CNN and Nokia Drive apps and features a built-in GPS that can be used for navigation without a SIM card.

Along with the announcement and a press release, Nokia made available a YouTube video showcasing the newest member of the Nokia Windows Phone family:

The Lumia 900 is not the first Nokia device to run the Windows Phone OS. Previously, Nokia outed the Lumia 710, an entry-level, $50 device that will be available on T-Mobile and AT&T, and the Lumia 800, a premium device not yet available in America (It's coming soon, according to Nokia representatives).

The Lumia 900 is, however, the first Nokia Windows Phone with 4G LTE, the faster mobile network that American carriers are racing to build.

“The introduction of the Nokia Lumia 900 with AT&T is another significant milestone in the ongoing rollout of Nokia’s global smartphone strategy,” said Chris Weber, president of Nokia Americas, in a statement. “The Nokia Lumia 900 is designed specifically with the U.S. in mind and the announcement of this collaboration with AT&T, in addition to other recent announcements, signifies a new dawn for Nokia in the U.S.”

Neither a price nor a release date were announced.

Though the Lumia 900 represents to AT&T a powerful bit of ammunition for its budding 4G LTE campaign, the stakes may be much higher for Microsoft and Nokia. Microsoft is pledging hundreds of millions of dollars in advertising for its flagging Windows Phone OS, which currently sits at under 5 percent adoption in the U.S., trailing Android devices, the iPhone and BlackBerry handsets by wide margins. Nokia, meanwhile, announced in February 2011 its intentions to drop the Symbian and Meego operating systems from its phones in favor of an exclusive multi-billion dollar partnership with Microsoft.

The Lumia 900 is the first real jewel of that partnership, a blue-ribbon smartphone tasked with competing with the likes of the iPhone 4S and the Samsung Galaxy Nexus in a crowded, well-entrenched smartphone market. If Nokia is to regain the massive market share it enjoyed in America in the early-2000s, or if Microsoft is to grab the mobile market share it currently enjoys in the PC business, then Nokia's newest batch of Windows Phones handsets will have to catch the attention (and wallets) of Americans in a way that previous attempts have not.

The Nokia Lumia 900 is perhaps the most significant attempt yet at gaining (or regaining) those crowns. Though the Lumia 900 will not be the final shot at denting the market, it will certainly be one of the loudest.